Basically (very basically) the toroidal vortex is the air that is not used of for combustion - it is designed to swirl around the outer edge of the combustion chamber to keep the flame path away from the combustion liner.

If the toroidal vortex flow is disturbed (blocked or damaged guide vanes etc) then the flame path can touch the combustion liner and eventually burn through.

I seem to remember the Rolls Royce Engine book has some decent diagrams of the airflow in the combustion zone.

The allison 250 uses more of a swirl (similar to the airflow produced by a propeller) than a toroidal vortex. Actually it uses two of them in opposite directions

If you click on this link and scroll down to the third set of pictures you will see an Allison 250 combustion liner with a very basic explanation of the swirl.The combustion chamber

Then inner ring of baffles (pressed flat flaps in the right hand picture) blow air in a counter clockwise (as you look at it) direction and the outer ring blows in a clockwise direction. This swirling primary air causes good mixing with the fuel for burning, it also shapes the flame and with the help of the secondary airflow, keeps it central in the chamber. 25% of airflow is used in the primary area (the holes on top in the left hand picture) 72% passes through the holes around the outside of the liner for cooling and to keep the flame away from the walls of the liner and the final 3% passes along the outside

from the diags there it appears i had assumed the complete opposite direction of flow for the toroidal vortex...(& we all know what ass.u.me does)

image credits to Mr Roger Marmion

so i was thinking that the flame at center of can to keep at most distance from can lining, airflow of flame would create too strong a force for the toroidal vortex to flow in opposite direction. Just as the high & low pressure systems will rotate in opposite directions allowing more fluid motion, my assumption that if strongest flow of (flame) air being pushed through the turbine that (logically) the inner part of torodial vortex would spin with the flame not against it as indicated at (b), very intriguing that it goes against the flow of the flame.

either way a pain to animate. many thanks to those who posted, send me a PM if you'd like a peek at what I've done so far